Questions tagged [digital-communications]

Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.

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37 views

Need help in computing the evolution of symbol error rate for uncoded OOK scheme over fading channels

I am trying to reproduce the results exhibited in Fig. 1. in the reference, i.e., "Error performance of coded FSO links in turbulent atmosphere modeled by gamma-gamma distributions" linked to (https://...
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1answer
54 views

Can anybody explain to me how to solve such questions? Constellation Diagram [closed]

i'm not able to proceed with such questions. If someone could explain how to solve such questions, would be a big help. Thanks.
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Connecting an industrial PLC to Android phone over a wire

Building an Android app that will take a picture and based on pixel values determine whether to continue operation or not (output true or false) to the PLC. It is a Mitsubishi FX3U-48 PLC and I don'...
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48 views

GBE (Gigabit Ethernet) Magnetic Coils Connection Order

I am designing a MEZ PCB and I need to connect the GBE coils to the assigned pins of single board computer's MEZ connector. My trouble is I do not want to use any more via for this connections. Hence, ...
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2answers
59 views

Preventing audio feedback in an underwater multiway intercom

I'm trying to transmit data(bytes) from a speaker (out) to microphone (in) via an FM modulated link. Now I have the problem that both will be used simultaneously (full duplex) and next to each other (...
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2answers
78 views

Is there a method to get the carrier from the recieved QPSK signal?

If we have given a signal and we know that is a modulated QPSK signal, can we recover the carrier if we know the carrier frequency fc. Edit: A clarification, I do not have to do it in hardware, a ...
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18 views

How to perform multiplication at the time series level for chirp signals

As the title said: How to perform multiplication at the time series level for chirp signals? In LoRa modulation, when received a chirp modulated signal, to demodulate it, LoRa will first multiple the ...
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13answers
4k views

Examples of fluid (including air) being used to transmit digital data? [closed]

We usually use electrons to communicate data across wires, and sometimes we use light also. Does anyone know of real world example systems that use fluids (including air) to do this, and the ...
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1answer
41 views

What is the transmission bandwidth for a BASK (Binary Amplitude Shift Keying) signal?

What is the transmission bandwidth for a BASK (Binary Amplitude Shift Keying) signal? Shouldn't it be infinity as short periods of sinusoids are used to depict 1 and 0 to depict 0?
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23 views

CAN Transciever kbps to Hz at TXD Pin

I am new to the CAN Bus and have designed an application example. The Transceiver I have chosen is TJA1044Gx. The transceiver data sheet says : I want to know if I have only Transceiver, Analog ...
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2answers
69 views

Can we band pass filter QPSK signal?

Consider we have QPSK signal with carrier frequency 10kHz. Generally, we demodulate or use matched filter on the the QPSK signal and recover the transmitted bit or the symbols. If the QPSk signal is ...
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7 views

How is n_pucch_2 in rrc layer computed

In LTE network I know that n_pucch_2 is used to indicate the resource index for pucch format 2/2a/2b. And I know its value is defined in higher layer. But how is the value computed and defined in the ...
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1answer
39 views

What is the minimum sampling rate for QPSK or what is the bandwidth of QPSK signal?

Consider we have created a QPSK signal with a carrier frequency 100kHz. Before applying matched filter or demodulation we need to take sampls from the received signal. So what is the minimum sampling ...
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1answer
31 views

Machine comms troubleshooting

While this may be suited for an automotive section I believe my question is better suited to this forum. I'm having OBD II comms issues and have a run a similar troubleshooting process to what's ...
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1answer
49 views

JSON for GSM Comm on STM32

I am making a remote monitoring system using STM32F1 MCU in which there are few digital and analog sensors attached and I would send their readings to a remote server periodically. Can I use JSON ...
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137 views

Strange I2C communication

I am currently trying to test the SHT3x series humidity sensors by Senserion. I have their EK-H4 evaluation kit to get data from the sensors. I can plug in the sesnsors provided with the kit, and all ...
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2answers
38 views

1-wire differentiate read from write

I've been reading documentation on 1-wire and I think I'm having a brainfart. How does the slave differentiate a read slot from a write slot? reference: https://www.maximintegrated.com/en/app-notes/...
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89 views

How to Low-Pass PDM Output Data

I have a PDM-Mems Microphone which provides me with 101010 data, the Microphone has a Clock of 3Mhz. I read the manual about how PDM is generated, but I haven't worked with digital filters yet and in ...
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1answer
29 views

Pairing vs Master-slave between BT Module to BT Module

If I take two identical BT modules, for example HC05 or HC06 then is it possible to pair the two modules with each other or is it like you need 1 master and 1 slave module for pairing? Edit: Now I ...
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1answer
68 views

Bluetooth vs BT Beacon [closed]

While trying to understand how BT devices work I came across another related term "BT Beacon". Is it same as BT communication or if a device is termed as BT beacon then it would have some specific ...
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0answers
48 views

What is the fieldbus for Unitronics PLC?

I am currently investigating the inner behavior of a PLC of the brand Unitronics. I identified several bus for the communication with actuators, other PLCs, etc (like Modbus or CANbus) One thing I ...
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10 views

finding the minimal length of a broadcasting frame in a channel(CSMA/CD)

i am unsure about this question. would appreciate your assistance with it. in the following CSMA/CD network with cable length L and propagation T. assuming that the signal is not decreasing and there'...
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2answers
69 views

Does direct GPIO communication between 2 microcontrollers requires pull up/down

If I want to use GPIO pins of two microcontrolles as a mean of simple communication (e.g. reporting an event by sending 1 or 0), Do I need to enable internal pull up or pull down resistors on any of ...
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80 views

Probing LPC bus with an FPGA yields gibberish — wiring problem?

I'm trying to repeat the TPM key dumping experiment by Pulse Security using a motherboard with Secure Boot and the same TPM1.2 chip onboard, equipped with Windows 8. However, when I connect the FPGA ...
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1answer
58 views

Finding the overhead and distance of an unknown code based on message making algorithm

for an information word M with m bits that is coded as following: M is coded into a word A using an unknown code that allows detection of not more than one error. the code word is the word obtained ...
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1answer
15 views

loading multiple shift registers from few pins

We want to load two 32 bit data shift registers without concatenating them using 4 control lines (SI1, SI2 clock, latch). It can be done by bit banging but can it be done using SPIs using only 4 lines?...
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23 views

Find Bit Error Rate and Eb/N0?

I have read about Bit Error Rate and Eb/N0 to find out how can I generate them. I understand BER but what confused me is Eb/N0. How can I find Eb/N0 values and the corresponding BER values. I have ...
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1answer
65 views

Signal placement in flat ribbon cable, FPC or FFC with digital and power signals

I want to interface different boards with FPC/FFC or ribbon cable and I was wondering about the placement of the signals in the cable. I plan to have a 39 signals FPC with : 1 SPI bus (SCK, MOSI, ...
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1answer
53 views

Visualise a bit pattern

My objective is to send a bit pattern of 1000 bits from one microcontroller (PIC or Atmel) to another one using the SPI method. How can I visualize the bit pattern so I can find the errors of ...
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1answer
37 views

Source generator for Satellite Tuner input

I need to design a source generator for a TV factory. They want to automatize the functional tests by applying a test module to the TV's at the end of the production line. All the peripherals of the ...
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1answer
43 views

What is the effect of redundancy coding on the bit error rate?

If I have a channel with bit error rate BER = \$10^{-3}\$ after modulation, but this is too high so I decide to add repetition coding. With 2 code words and block length of 3 such that I have a ...
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3answers
90 views

Choosing best bus and protocol for ~128 clients over the wire

I am up to design system with ~128 MCUs communicating to one MCU master. Communication will be bidirectional. Data will be mostly sensor reads, but I plan to use the bus also as communication method ...
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1answer
106 views

How do I stop signal looping with I/O port in this communication system

I am still a student. When I am designing communication system I am facing this problem: As shown in the figure I need to communicate with Master and Slave. But Master and Slave have single I/O port ...
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3answers
138 views

How is companding different from pre-emphasis and de-emphasis?

What I know is that interference increases linearly with frequency and thus noise power is concentrated at higher frequency. So, to reduce noise, pre-emphasis and de-emphasis filters are used which ...
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1answer
272 views

Signed and unsigned numbers in verilog

I understand the concept of fixed point and multiplying signed with unsigned by sign extension the unsigned number with 1 bit of '0' so it will be signed always positive number, But my question If I ...
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1answer
92 views

UART Transmit issue in VHDL

I'm working on a UART transmit process (uart_transmit) in VHDL (115200 baud, 8 data bits, 1 stop bit and no parity). I need the transmit line ...
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1answer
166 views

Are horizontal and vertical back porches required for digital video, and if so, why?

The necessity of vertical and horizontal front and back porches in analog video seem fairly intuitive to me, but why are they necessary for digital video at all? In this LCD module data sheet and this ...
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1answer
87 views

In wireless communication, what is “channel length”?

In wireless communication, I am confused about what people are referring to when they use the term 'channel length.' Can someone explain the term or provide me a definition?
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64 views

High data rate (~1-5 Mpbs) Point to Point Radio

I'm working on a rocket project at my University, and am trying to find a point to point / point to multipoint radio capable of a hopefully 1-5 Mbps data rate between a ground station a directional ...
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2answers
150 views

What device can convert (EEG) voltage data to real voltage? [closed]

I seek a device that can be programmed to output physical voltages based on a set of datapoints. For example: ...
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1answer
51 views

Inverse Z-transform Problem [closed]

I'm rather stuck trying to compute the inverse Z-transform y[n] of the function below. I'm having trouble selecting the correct formulas from the table to achieve the right solution. Any help with ...
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1answer
86 views

Ringing issue on I2C FM+ bus between MCU and few sensors - Power supply issue?

I'm experiencing some issues while probing a problematic I2C bus on the oscilloscope. We want to interface several TLV493D-A1B6, with a STM32L4 (we are working as well on STM32F4 and have the same ...
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3answers
55 views

Practical Limitations to 1-Wire Communication Speed [closed]

What are some practical limitations to the speed of a 1-Wire interface?
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2answers
160 views

Can someone explain the use of the transistor in this circuit?

I came across a schematic which implemented a 1 Wire interface. However, this 1-Wire interface circuit also includes a transistor connected as shown in the picture. Can somebody expain why this has ...
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5answers
160 views

RS485 IC Termination Resistor Configuration

I've made a mistake on a design, that went into production... It was built like the drawing on the left, with R702 to 5V and R703 to GND, it should have been backwards... like the drawing on the ...
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0answers
58 views

Derivation of stability criterion for type 3 digital PLL

Could anyone help to derive the following expression (4.23) which is the stability criterion for type 3 digital PLL ? Note: Screenshots are taken from Floyd Gardner's book : Phaselock Techniques 3rd ...
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1answer
31 views

What are cost-effective and ways of providing global communication between two devices besides internet and SMS?

I am currently in the process of building a system which allows vehicles to send information back and forth with an Arduino. The main problem I am facing right now, is that the current implementation ...
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2answers
57 views

Geometric representation of GMSK signal

Can anyone provide me the geometric representation of GMSK signal? Also, am I correct in saying that bit energy of GMSK is same as its symbol energy since MSK is a binary modulation scheme with only ...
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1answer
56 views

Printer Data Cables with *suspected* IC boards [duplicate]

I've one found of those printer data cables that have some kind of pair integrated circuit along them, one at each end just before the plugs, I was wondering if there is a less invasive way of ...
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1answer
145 views

Asynchronous FIFO in clock domain crossing

Clock domain crossing issue can be solved by using asynchronus FIFO with input frequency f1 is of the source domain and f2 is of the destination frequency. If the data is sent in bursts, depth can be ...